I regularly receive emails from gardeners who panic at the thought of bringing ants into their home by accident.
For them, there is no question of bringing cut flowers in from the garden or of bringing houseplants that spent the summer outdoors back indoors, at least not without a thorough treatment with a strong insecticide. They even regard vegetables from the kitchen garden with suspicion and inspect them thoroughly—outdoors!—before bringing them in, so much are they afraid to bring ants in at the same time.
But if that’s your fear, relax. There is no reason to fear bringing ants indoors. They’re actually totally harmless in that situation.
To understand why an ant brought indoors by accident is so harmless, you have to know a bit more about ants in general.
Ants are social insects that live in a colony (nest) that can be found underground, in a tree trunk, hidden among rocks, etc. The ones you see in the garden (and that you could therefore bring indoors by accident) are all worker ants. Their role is to forage for edible products and to bring them back to the nest to help feed the queen, the larvae she produces and the other workers. Workers are sterile and produce no young. They simply can’t settle in your house and start a new colony.
If you bring an ant indoors by accident, it will only try to find its way back to its nest. But bringing it indoors so suddenly will likely completely disorientated it. It won’t know where to go. It doesn’t even have the intelligence to look for a way out, but will wander confusedly until, after a few days, it dies from exhaustion and hunger, probably sight unseen in a corner where your broom or vacuum cleaner will quickly remove it. It carries no harmful diseases, won’t bite unless provoked, and there is no long-term risk for your home or for you, as it will not start a new nest.
If you find a lost ant wandering pitifully in your home, pick it up with tissue paper and move it back outdoors … or squash it. It needn’t bother you any more than that.
Foraging Ants: A Different Situation
When an ant finds its way into your house all by itself and discovers your pantry or another source of food, that’s a very different situation.
First of all, it won’t be disorientated. Like Hansel and Gretel dropping bread crumbs to find their way home, it left a special pheromone all along the path it followed, one that will tell it exactly how to return to its nest. If it finds something to eat, it will head back, leaving a new “I’ve found food” pheromone trail. This will inform the colony’s workers of the discovery and they can then follow the trail to the source of food.
Now you do have a problem, a never-ending line of ants raiding your kitchen and going to and fro. You can stop the flow by plugging the hole through which the ants penetrate the house (the best solution) or, if you can’t find it, by setting out ant traps or dusting door frames and window bases with diatomaceous earth.
Keeping Lost Ants Out
If, spite of my explanations, you still shudder with horror at the idea that you might accidentally bring in a completely inoffensive worker ant into your home, the problem isn’t the ant, it’s you! You’re suffering from a phobia, an irrational fear, and phobias are hard to overcome. If so, did you know that it’s very easy to prevent accidentally bringing ants indoors?
If you bring cut flowers, houseplants, vegetables, etc., gather them, leave them by the back door … and bring them in early in the evening. Any ants that might frequent them wisely return to their nests at the end of the day. So, if you bring in objects at dusk, they won’t have any ants on them.